On the whole, information is stored in the memory of a computer and/or an external storage device. The information can be private or confidential. In order to prevent unauthorized use, it is therefore desirable to control access to this information. Such a controlled access to computer data can be realized by providing physical (hardware) means for preventing the use of the computer itself or input/output (I/O) devices on a computer system, or by providing software means for restricting access, such as a routine that confirms a user's knowledge of a password before granting that user access to information contained in the computer system.
One commonly-used method for restricting user interaction with a computer is to provide a “password lock” function, which is executed in a central processing unit (CPU) itself or a keyboard controller. Typically, when a keyboard controller is in a “password lock mode”, no communication between the keyboard and the CPU of the computer is allowed unless a password is first entered to remove the controller from the “password lock mode”. An example of a computer that has a password lock function is the IBM PS/2 desktop models. A password function is commonly included in the power on or boot-up routine executed by the CPU when a power switch is turned on. The password is stored in a non-volatile memory device, rather than a hard disk. When the computer is turned on, machine language code in a startup read only memory (ROM) part of memory is executed, and it is required for the user to input the password. The input password is compared to a password stored in the complementary metal oxide semiconductor (CMOS) random access memory (RAM). If the passwords match, the remaining startup code is executed, and the system becomes operational. If the passwords do not match, however, the startup execution is halted and the system is left inoperable, thereby preventing unauthorized use of the system.
Another commonly used method for restricting a user interaction with a computer is that wherein a system administrator provides a password enabling a user to log in to the computer. This is typically more important in a network system operating with a client operated by a user and a server executing a process according to a requirement of the client. This function is also provided during log on of an operating 8 system (e.g., Windows), such as a routine to set and confirm a user identification number (hereinafter referred to as “ID”) and a password. Windows is a registered brand of The Microsoft Corporation, as is Windows 95 or Windows 98 herein.
In order to perform remote control of a computer system having such a security function to protect information, it is necessary to consider the security function provided during confirmation of the complementary metal oxide semiconductor (CMOS) password and log on of the operating system. If such a security function is not considered, a user has to personally input a password during the confirmation and the log on thereof, although the computer system is remotely booted-up by the remote controller. As a result, the remote control of the computer system can be disadvantageous.
U.S. Pat. No. 4,959,860 to Jeffrey S. Watters et al. entitled Power-on Password Functions for Computer System, discloses a RAM (random access memory) receiving power from a battery that maintains the password when system power is turned off. However, Watters '860 does not refer to a security function of a computer operated by a remote controller. Watters '860 discloses a power-on password security function for a digital computer system that allows the system software to distinguish between authorized and unauthorized users. Safeguards are provided to prevent corruption of password data which could lead to a lock-out of authorized users, and redundant checks allow the security function to operate even when first-level checks fail. The latter patent discloses a battery-powered RAM storage area used to hold the password when the system is turned “off”, and that storage area is protected against being accessible by unauthorized users when the system is turned “on”.
U.S. Pat. No. 4,800,590 to Vaughan, entitled Computer Key And Computer Lock System, discloses a computer access system that includes a password generator and a lock computer connected to receive passwords generated by the password generator and to grant access to a host computer when a password from the password generator matches a password separately generated by the lock computer. The patent discloses that the password generator and the lock computer have corresponding pseudo-random number sequences stored in memories. The password generator and the lock computer have synchronized clocks, which define time intervals. It is further disclosed that, during a given time interval, entry of a personal identification number in the password generator will cause the password generator to generate a unique password from the random number sequence in the memory and time interval information from the clock. The user transmits the generated password to the lock computer, which independently generates a comparison password from the corresponding pseudo-random number sequence stored in the memory, and the time interval defined by the clock. If the passwords match, access to the computer is granted by the lock computer. Since the valid passwords change with each time interval, subsequent use of an intercepted password will not grant access to the computer.
U.S. Pat. No. 3,890,601 to Pietrolewicz, entitled Password Operated System For Preventing Unauthorized Or Accidental Computer Memory Alteration, discloses that manipulation of a digital computer magnetic memory is locked out to prevent unauthorized or accidental erasure. The memory is provided with a unique password. It is disclosed that, unless the correct password is present in the computer, or entered into the computer by the operator, the computer will not run and the memory cannot be altered.